Fabrication and performance of catalyst-coated membranes by layer-by-layer deposition of catalyst onto Nafion for polymer electrolyte membrane fuel cells

Abstract

In this contribution, four comparative methods are described for the preparation of catalyst coated membranes (CCMs) via using layer-by-layer (LbL) technique. In the first method. LbL composite membrane is immersed into H2PtCl6 solution followed by reduction to metallic Pt. Secondly, Pt-C (Hispec 3000) dispersed in the positively charged polyelectrolyte is assembled onto the membrane support. Thirdly, anionic polyelectrolyte with external salt is used for the preparation of CCM. In the fourth method, reductive precipitation of platinum salt loaded on Vulcan XC complexes within LbL multilayer in the presence of Nation solution takes place. From SEM analysis, it is observed that the polyelectrolytes are deposited onto both sides of the pre-treated Nafion (R) 117 membrane successfully with Pt loadings of 0.023 mu g cm(-2) and 0.15 mu g cm(-2) for CCMs prepared according to method 1 reduced in 10 and 30 min, respectively. Single cell performance of MEA-6 based on CCM (PAH/PSS-H2PtCl6-Vulcan XC72-Nafion) prepared according to method 4 displays the best output performance (98 mW cm(-2)) due to the improved contact between the catalyst layer and the membrane. Furthermore the cell performance of MEA-6 is significantly improved (18%) due to creating new path for fuel and catalyst interaction (three phase boundary) compared to pristine Nafion (R) 117 based MEA. (C) 2011 Elsevier B.V. All rights reserved.